CVE-2026-77274: mcp-atlassian SSRF Protection Bypass Vulnerability
Summary
CVE-2026-77274: MCP Atlassian: SSRF Protection Bypass. Affects mcp-atlassian versions < 0.22.0. Fixed in 0.22.0. How to fix ↓
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Background
mcp-atlassian is a Python package designed to facilitate integration with Atlassian products such as Jira and Confluence. It provides functionalities for managing project workflows and automating tasks within these platforms. However, the package has a vulnerability that allows attackers to bypass server-side request forgery (SSRF) protections, potentially exposing internal services.
Vulnerability Detail
The vulnerability arises from a flaw in the 'validate_url_for_ssrf()' function, where the SSRF protection can be bypassed using a URL that includes a backslash before userinfo-like syntax. This allows an attacker to manipulate the URL, leading to requests being sent to internal services instead of the intended external host. The technical issue lies in the mismatch between how the URL is parsed for validation and how it is processed for the actual HTTP request, allowing restricted hosts to be targeted.
How To Fix
Latest published version: 0.23.1 as of 23 Oct 2026
pip install --upgrade "mcp-atlassian==0.23.1"Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
0.22.0
This is the first release that contains the fix.
pip install --upgrade "mcp-atlassian==0.22.0"Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, avoid using URLs that contain backslashes in the userinfo section. Ensure that any Jira or Confluence URLs provided do not include such syntax to prevent potential exploitation until the package can be updated.
Conclusion
The mcp-atlassian package has a significant SSRF protection bypass vulnerability (CVE-2026-77274) that can be exploited by attackers to access internal services. It is crucial to update to the patched version (0.22.0 or later) to mitigate this risk. Users should also be cautious with URL inputs until the update can be applied.
See every vulnerability recorded for mcp-atlassian →
FAQ
Server-Side Request Forgery (SSRF) is a vulnerability that allows an attacker to send crafted requests from a vulnerable server to internal or external resources, potentially leading to unauthorized access or data exposure.
You can check if your application is affected by using the Vulert playground at Vulert Scanner, which allows you to monitor and alert for open-source vulnerabilities without requiring signup.
An attacker could exploit this vulnerability to access internal services, leading to data leaks, unauthorized actions, or further exploitation of the internal network.
Yes, the CVSS score for this vulnerability is 8.8, indicating a high severity level.
If you cannot update the package right away, ensure that you do not use any URLs with backslashes in the userinfo section to mitigate the risk of exploitation.
References
Related vulnerabilities
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